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human torso rib cage

Image: “The human torso” by Physiology for young people adapted to intermediate classes and common schools. by Woman’s Christian Temperance Union. National Department of Scientific Instruction. – https://archive.org/details/physiologyforyo00instgoog. License: Public Domain


Definition of Thoracic Traumatic Injuries

The thorax is the region of the body that is located between the neck and abdomen. Traumatic injury to the chest, also known as thoracic traumatic injury, is any form of injury sustained by the chest due to a blunt or penetrating trauma. The thorax encompasses vital organs, such as the heart, major blood vessels, and lungs. Injury to any of these vital organs is associated with significantly higher mortality rates.

Common Thoracic Traumatic Injuries

Traumatic pneumothorax is defined as the abnormal collection of air in the pleural space due to a laceration of the lungs.

Rib fracture and flail chest: Rib fractures are commonly seen in patients who have sustained a blunt trauma to the chest.  A flail chest is defined as at least two fractures per rib in two adjacent ribs which would produce a free segment.

Pulmonary contusion: Blunt chest trauma may result in a lung contusion, in which blood accumulates in a small part of a lung lobe, in the whole lobe, or even across multiple lobes. A patient with rib fractures should be investigated properly to exclude the possibility of pulmonary contusions. When we say investigated properly, we are referring to ordering a non-contrast chest computed tomography scan.

Epidemiology of Thoracic Traumatic Injuries

Approximately 13.4% of those who sustain polytrauma injuries are expected to have a thoracic traumatic injury.

The estimated incidence of rib fractures in the United States was reported to be around 346 per 100,000 population in those aged 50 years or older. The incidence in other age groups is largely unknown, most likely because of issues with under-reporting.

Etiology of Thoracic Traumatic Injuries

Motor-vehicle accidents are the most common cause of thoracic traumatic injuries. Gunshots and stabbings are among the most common causes of penetrating thoracic traumatic injuries.

The single most common cause of traumatic pneumothorax, however, is lung laceration. Lung lacerations are usually the result of a traumatic rib fracture; however, they can also be seen in patients who sustain a penetrating chest injury.

Rib fractures are more common after a blunt trauma to the chest. For instance, falling may cause rib fractures. While this is unlikely in healthy young individuals, due to higher rates of osteoporosis, elderly people are at an increased risk of developing rib fractures after falling down.

Classification of Thoracic Traumatic Injuries

Based on the mechanism of injury

Based on the nature of the point of contact with the thorax, thoracic injuries can be classified as either blunt or penetrating. Associated injuries, the diagnostic workup, and management are all determined by the mechanism of injury. Therefore, it is important to ask about this while taking the medical history from the patient or those accompanying the patient.

Based on the injured organs

Traumatic thoracic injuries include cardiac, major-vascular, lung, chest-wall, airway, and esophageal injuries.

Traumatic cardiac injuries include traumatic cardiac arrest, myocardial contusion, tamponade, and bloody pericardial effusion. The ascending aorta and the thoracic aorta may be injured in patients who have sustained a penetrating chest trauma. Blunt trauma to the chest may result in dissection of the aorta. Airway injuries include tracheobronchial injuries. 

Pulmonary injuries include lung contusions, hematomas, and lacerations. Pulmonary injuries may be associated with a pneumothorax, hemothorax, or hemopneumothorax.

Chest-wall injuries include rib fractures, sternum fractures, and fractures of the shoulder girdle. Flail chest is another example of a chest-wall traumatic injury. Chest-wall contusions and bruises are usually seen after blunt chest trauma.

Pathophysiology of Thoracic Traumatic Injuries

A pneumothorax is the result of air getting trapped in the pleural space after a lung laceration. This is associated with poor inflation of the lungs, and a decreased ability of the lungs to oxygenate the blood. A tension pneumothorax occurs when there is too much air in the pleural space, which results in decreased venous return to the heart. Therefore, a patient with a tension pneumothorax will have compromised circulation.

Flail chest: The fracture of multiple rib bones is referred to as flail chest. It interferes with breathing and causes ventilatory insufficiency.

Pulmonary contusion: The development of pulmonary contusions is based on the confluence of three factors. It includes the inertial effect (the presence of shredded alveolar tissue), the implosion effect (pressure waves causing the bubble-loaded alveoli to explode), and the spalling effect (when the alveoli burst as they meet the shock wave).

Symptoms of Thoracic Injuries

Pneumothorax: The clinical feature of pneumothorax is chest pain that is rapid in onset. It is one-sided and associated with severe difficulty in breathing.

Rib fracture: Rib fractures are generally asymptomatic, but in some cases they may represent serious injury to the internal organs of the body. A first-rib fracture, although rare, is often associated with spinal injury. The location of the rib fracture usually indicates which underlying organs may have sustained injury. Rib fractures are associated with swelling and bruising—symptoms often associated with flail chest—and pain in the chest, along with breathing difficulties and shortness of breath.

Pulmonary contusion: This injury presents with chest pain, along with coughing up blood. The patient experiences difficulty in breathing along with reduction in cardiac output. Another symptom includes decreased breath sound during auscultation.

Diagnosis of Thoracic Injuries

The diagnosis of blunt injury requires the assistance of radiological techniques, such as ultrasonography and computed tomography (CT) scans of the chest. In many cases, penetrating injury can be diagnosed simply through clinical examination and medical history.

Pneumothorax

In most cases of pneumothorax, the diagnosis can be established by simple clinical examination. At that time, the physician may notice a dampening of breathing sounds due to a decrease in the transmission of lung sounds through the collection of air. The percussion of the chest wall results in hyper-resonant vibrations.

Additional radiological examinations, such as a chest X-ray and CT scan, can be performed to confirm the diagnosis.

Rib fractures and pulmonary contusions

When a rib fracture is found on a chest X-ray, the probability of pulmonary contusion increases. This is especially true if the patient has difficulty maintaining peripheral oxygen saturation within the normal range despite the administration of high-flow oxygen therapy.

In such cases, a CT scan is indicated to exclude or confirm the diagnosis of a pulmonary contusion. It is important to document the extent of the pulmonary contusion seen on the CT scan.

Management of Thoracic Traumatic Injuries

General management principles

Adequate fluid and supplemental oxygen therapy are usually needed in patients with significant thoracic traumatic injuries.

Pain management forms an integral part of the therapy. Opioids are avoided wherever possible due to the risk of respiratory depression.

Penetrating injury is managed conservatively, in most cases through the use of a chest drainage tube.

Penetrating injuries may be associated with vital organ injury. Accordingly, surgical treatment must be tailored to the specific type of injury.

Management of the specific forms of thoracic traumatic injuries

Pneumothorax

The management of pneumothorax depends on the amount of air that has collected in the pleural cavity.

A small pneumothorax is likely to resolve on its own, whereas tension pneumothorax should be first treated with an emergency needle thoracotomy followed by a definitive chest tube.

Rib fractures and flail chest

Rib fractures do not require any special form of treatment other than pain control.

Flail chest is associated with severe pain. Intercostal nerve blocks may be needed. Positive-pressure ventilation is indicated in severe cases of flail chest.

Patients with a flail chest should undergo chest physiotherapy. Chest physiotherapy prevents lung infection and chest-wall muscular atrophy.

Internal fixation of the fractured ribs in a patient with a flail chest provides definitive treatment; however, this is usually not needed.

Pulmonary contusions

Adequate supplemental oxygen therapy and fluid therapy are all that is needed. Mechanical ventilation may be needed in more severe cases.

Complications of Thoracic Traumatic Injuries

A simple pneumothorax may progress to the more life-threatening condition known as a tension pneumothorax. Rib fractures usually have a good prognosis; however, they may also be associated with internal injuries such as pulmonary contusions. A flail chest predisposes the patient to an increased risk of developing pneumonia due to the blocking of the smaller airways caused by impaired ventilation.

Pulmonary contusions are associated with a high mortality rate, estimated to be around 15%. Moreover, pulmonary contusions may become infected.

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